Study investigates potential for biomass from grass in ND

By Lisa Gibson

A study in North Dakota aims to determine what types of grasses can sustain the state's soil and climate conditions while yielding the most biomass.

The North Dakota State University Central Grasslands Resource Extension Center in Streeter has teamed up with the North Dakota Game and Fish Department, the North Dakota Commerce Department and the Department of Agribusiness and Applied Economics, among others, to conduct the 10-year study. It will evaluate production, carbon sequestration, economics and longevity of perennial forages in western and central North Dakota.

Several 15-by-30-foot plots at five locations were seeded with the same 10 treatments, according to Paul Nyren, center director. Dry plots were set up near Hettinger, Minot, Williston, Streeter and Carrington, and one irrigated plot near Williston. The harvesting began in 2007, but this is the first year researchers will begin harvesting one set of plots every other year. "The hypothesis is that you might be able to get an increase in yield and save enough money by harvesting every other year to make it economically feasible," Nyren said.

Federal funding for the project is funneled through the Natural Resources Trust. The agency focuses on maintaining cover on land, another reason the researchers will begin harvesting only every other year on some of the plots, Nyren said.

The project's objectives are to determine the biomass yield and select chemical composition of perennial herbaceous crops at several locations; determine the optimum harvest dates for maximum biomass yield and maintenance of the stands; compare annual and biennial harvest for total biomass yield and maintenance of the stands; evaluate carbon sequestration and storage of the various perennial crops; and evaluate the economic feasibility of the various perennial herbaceous energy crops with competing crops in the surrounding area, according to the research center's Web site.

Grasses used in the study include switchgrass, wheat grass, wild rye, blue stem and combinations of some grasses. The best yields of sunburst switchgrass came from the Williston irrigated plots, which yielded about 5.75 tons per acre in 2007 and 7.28 in 2008, but Nyren said the conclusions are difficult to describe. "The question is: what is that worth as a biofuel crop?" he asked. Studies show that to be economically feasible, biomass yields need to be worth about $75 per ton, he said. "We have to ask: what are companies going to be willing to pay?"